Marine terminal mooring

ABSTRACT

The invention relates to a marine terminal positioned at or adjacent to an offshore body of water being adapted for anchoring barges, vessels and the like while the latter are connected with one or more sources of fluid to be transferred. Said vessels are fixedly located in the water by a plurality of anchor means disposed at discrete intervals about the floating vessel. Each anchor means includes a holding member imbedded at least partially into the ocean floor and connected to the floating vessel by an anchor rode such as a chain, cable or the like. A mooring means is likewise connected to the imbedded anchor by a stabilizing member which includes a weighted body normally supported at the ocean floor and a buoyant column pivotally connected at one end to the body buoyed whereby to maintain an upright position.

United States Patent 91 Mott et al.

[ 51 Jan.23, 1973 1 MARINE TERMINAL MOORING [75] Inventors: George E. Mott, Metairie; John T.

Loggins, New Orleans, both of La.

[73] Assignee: Texaco, Inc., New York, N.Y.

[22] Filed: Nov. 14, 1969 [21] Appl. No.: 876,926

UNITED STATES PATENTS 3,103,209 9/1963 Bolton ..l14/230 3,118,155 1/1964 Siegel ..9/8 OP 3,360,811 1/1968 Bartlebaugh ..9/8

Primary ExaminerTrygve M. Blix Attorney-Thomas H. Whaley and Carl G. Ries [57] ABSTRACT The invention relates to a marine terminal positioned at or adjacent to an offshore body of water being adapted for anchoring barges, vessels and the like while the latter are connected with one or more sources of fluid to be transferred. Said vessels are fixedly located in the water by a' plurality of anchor means disposed at discrete intervals about the floating vessel. Each anchor means includes a holding member imbedded at least partially into the ocean floor and connected to the floating vessel by an anchor rode such as a chain, cable or the like. A mooring means is likewise connected to the imbedded anchor by a stabilizing member which includes a weighted body normally supported at the ocean floor and a buoyant column pivotally connected at one end to the body buoyed whereby to maintain an upright position.

3 Claims, 4 Drawing Figures PATENTEDJAM23 ma 3.712.260

SHEET 2 0F 2 1 MARINE TERMINAL MOORING BACKGROUND OF THE INVENTION With the advent of larger ocean-going tankers, barges and other liquid carrying vessels, it has become necessary to provide means for such vessels to load and unload at a distance from the shore. This is true, particularly in the instance of super tankers and barges having overly large hulls.

A ready expedient for accommodating such vessels has been through the use of marine terminals positioned offshore from a refinery of fluid storage area. In one arrangement found to be practical, the terminal facility includes at least one shore based storage tank or floating means such as a vessel or large tanker for holding an amount of the fluid to be transferred. In the instance of the petroleum industry, the fluid would be in the form of crude or refined liquid petroleum, or the various component thereof after full or partial refining of the crude material. Thus, the marine facility quite often is adapted to accommodate a number of tankers adapted to separately carry the respective refined products.

The normal means for fixedly positioning such marine terminals is by anchoring the same to the floor of the offshore body of water. To avoid undue movement of the floating vessel, which would tend to disrupt the normal liquid flow by breaking or tangling subsea conduits, the vessel is held in place by a plurality of peripherally disposed anchors.

This form of anchoring method embodies the disadvantage of rendering the storage or transport facility relatively immovable in response to wind and water forces. It is nonetheless considered desirable and among the most efficient for transferring liquid petroleum products since it avoids the problems associated with the vessel swinging about a mooring.

The usual procedure for receiving or discharging a cargo from the marine terminal, is by mooring the tanker or other cargo carrying vessel a distance from the storage facility. Submarine lines connected to the facility are then communicated with the tanker whereby the liquid can be controllably pumped into or from the latter.

One drawback to the herein described marine facility is the continuous relative movement between the storage means and the tanker. Such movement, both horizontal and vertical, tends to drag the anchoring chains, which lie at the floor of the body of water and are partially imbedded by their own weight in the same. In the instance of a rocky or sandy ocean bottom, excessive losses have been realized due to downtime on the facility, and in repair costs as a result of the continuous abrasive action of the chains as they undergo horizontal and vertical displacement.

Such movement is realized whether or not a vessel is moored. It is understandable, that so long as the chain is exposed to an abrasive material at the ocean floor whether sand, mud, or other, the latter will provide a continuous source of abrasive wear between links. Further, the wear will persist so long as the chain is subject to even the ordinary and restricted movement of the moored or the storage vessel even under relatively calm conditions.

It is therefore one of the objects of the invention to provide a marine terminal adapted for accommodating one or more cargo carrying tankers at an offshore position. A further object is to provide anchoring means for a vessel during the transfer of fluid to or from the latter from a storage facility. A still further object is to provide a buoyant mooring system connected to a fixedly positioned anchor, and having means in the system to resist harmful abrasion to moving chains at the ocean floor.

DESCRIPTION OF THE DRAWINGS In the drawings, FIG. 1 illustrates a marine facility of the type contemplated including an oil storage means located adjacent to an offshore mooring site. FIG. 2 illustrates the disclosed facility having a tanker moored thereto. FIG. 3 is similar to FIG. 2 illustrating the position of a vessel mooring column when subjected to excessive strain by a moored vessel. FIG. 4 is an elevation view in cross-section showing the mooring column.

In overcoming the herein mentioned problems, and in achieving the foregoing objectives, there is presently provided a marine liquid storing terminal including mooring means adapted to accommodate one or more floating vessels. The shown embodiment includes a shore based facility such as a refinery, tank farm, or the like. A moored vessel is held in place at the offshore location by anchors surrounding said vessel and imbedded in the ocean floor. The mooring means is provided with a partially flexible anchor rode, including rigid and nonrigid portions extending to each of the previously mentioned anchors. Each rode further incorporates a stabilizing member embodying an elongated, buoyant column extending upwardly from a heavy base member at the ocean floor, to a position above the ocean s surface.

As the floating ship is moored to the upper end of the buoyant arm or column, the latter, being pivotally connected to the submerged stabilizing or base member, will be laterally displaceable. Thus, in response to movement of the moored vessel, the column will assume a submerged, canted position. In the event excessive strain is applied by the moored vessel as by turbulent water or extremely stormy conditions, the excessive loading will cause the mooring column including the heavy base member, to be lifted in its entirety from the ocean floor although still exerting a continuous downward force.

In either instance, mooring chains connected to the imbedded anchor securing both the mooring column and the vessel, will be subjected to a minimum amount of chain displacement. The effect will be to minimize or preclude wear on the chains as a result of abrasive action normally prompted by the presence of said or other gritty materials around and between the chain links. Further, any displacing force applied to the anchor will be minimized since the force is laterally applied so long as the chain remains at the ocean floor.

Referring to FIG. 1, a marine terminal of the type contemplated isherein shown as comprising a floating transport vessel 10 moored in an offshore body of water. The latter is generally adjacent to, or remote from a land based storage area 11 such as refinery or a tank field. Vessel 10 can be .connected as welLto aplurality of subsea well heads or remote fields to receive flows of crude oil therefrom.

Usually the floating vessel is communicated with one or more sources of crude or refined petroleum products by a subsea conduit system 12. The latter is generally of a permanent nature formed of rigid pipe and/or flexible hose and positioned at the ocean floor being at least partially imbedded in the latter.

To simplify the conduit distribution system 12 and its connection to vessel 10, the latter is positioned as rigidly as is feasible by a plurality of anchors l3, 14, 16, 18, 19 and 21. The latter are disposed about vessel 10 at discrete, peripheral intervals and spaced from the vessel a suitable distance to provide maximum mooring ability with minimum strain on the mooring rodes or cables.

Since the anchored transport vessel is relatively stationary with respect to direction, it is preferably aligned on installation to the most favorable position with regard to prevailing wind and water movement. However, it is appreciated that neither of these elements of nature are constant and consequently the vessel will be subjected on occasion to excessive displacing forces.

Referring to FIGS. 2 and 3, each anchoring connection as for example anchor 16, includes a relatively heavy anchor chain 22. One end of said chain connects to an outer wall of anchor 16 by means of a shackle or other appropriate connection. Anchor 16 can be of the pile type which is imbedded by driving the same into the substratum a sufficient distance to afford necessary holding power. Said anchor can also be of the more conventional type adapted to establish a holding grip in the ocean floor. It is appreciated however that the type and number of anchors used about the vessel 10 will be determinable in accordance with the composition of the substratum into which the latter are imbedded. At least a portion of the chain 22 will be supported by the ocean floor and in most instances the chain will be of such a weight as to become imbedded in the soft soil. A float 29 is connected to anchor chain 22 by a line 23 a sufficient distance from pile 16 to permit the chain to be raised to the surface for locating the anchor and replacing the chain.

Mooring column or buoy 24 to which floating vessel such as a tanker or barge 10 is temporarily connected,

for transferring cargo to the latter, includes basically a weighted foundation pad or base 27 to which the elongated column or arm is pivotally connected. Foundation pad 27 is spaced remote from anchor 16 and in one form can consist of a relatively heavy concrete block. Other forms of foundation members can be utilized to position column 24 as will be herein noted. As shown particularly in FIG. 4, foundation pad 27 is provided with one or more external rings or staples 28 to which the other end of anchor chain 22 is connected by a shackle 31 or similar means.

In the normal ship mooring arrangement, the anchoring chain or rode would extend directly from anchor 16, upwardly to the tanker l0 and be fastened to the latter. Thus, and as previously noted, continuous movement of the vessel in response to water forces would result in said chain being shifted continuously about the ocean floor. Eventually, connecting links in contact with the bottom would gradually reach the point of breakage as a result of abrasive material becoming imbedded between the contacting surfaces of the respective connecting links.

Referring again to FIG. 4, column or arm 24 is formed of a relatively elongated, rigid connector which functions in one respect as a buoy in that it normally a'ssumes an upright position in the body of water. In one embodiment said column 24 comprises an elongated, heavy walled tubular member having a pivotal connection at the lower end which operably engages a corresponding fitting at foundation pad 27. A number of such flexible or universal connections are well known and widely used. However, for the purpose of exemplifying the instant description, a ring 32 is imbedded in foundation pad 27, preferably projecting from the upper side thereof. Said ring 32 is connected in turn to an end fitting 33 depending from the lower end of column 24 by an intermediate link 34 which permits free pivotal movement of said column 24 about its connecting point to base 27 Column 24 is formed of a relatively heavy walled steel tubing which is equal to or exceeds the tensile strength of the anchor cable 36. Column 24 is further provided with a plurality of transverse water tight bulkheads 37 and 38 whereby to form individual longitudinal compartments 39, 41 and 42. The latter in turn are filled with a light buoyant material such as expanded foam thereby assuring the column a degree of buoyancy even though accidentally fractured whereby the wall of the column would be broken to permit inleak of water. While not entirely necessary, arm 24 can be provided with a ballast medium in one or more of the lower compartments.

The upper end of the column 24 is provided with one or more mooring staples exemplified by a cleat 35 shown, or one or more peripherally spaced staples, depending from the column sides and which are adapted to receive mooring lines 36 from vessel 10.

As shown in FIG. 4, under normal conditions and when not being utilized as a mooring, column 24 assumes a generally upright, buoyed disposition in the body of water. Its position would of course be contingent on the tide and water turbulence. In such position upper cleat 35 is disposed sufficiently beyond the water's surface when the latter is at its highest point to facilitate connection to bow line 36. After the latter has been connected and as shown in FIG. 3, tanker 10 will be positioned by varying the bow line length to cause the column to be canted to an offset position. Simultaneously, tanker 10 will be further limited in movement by similar lines extending outwardly from the vessel to anchors 13, l4, 16, 18, 19 and 21 whereby the vessel will be restrained in all directions.

Referring to FIG. 3, under extraordinary conditions, tanker 10 will be subjected to excessive displacing forces from one side such as high waves or strong winds to the extent of moving the tanker whereby to apply a dislodging force to the mooring columns 24 on one side of the ship. Under such circumstances, the tensional stress along respective connecting lines, through the columns 24 and their pivotal connections will cause the heavy foundation member 27 to be raised from its normally partially imbedded position. The function of said member 27 then is to in effect apply a temporary damping force to counter the displacing force against the vessel. The said damping force will be maintained by foundation 27 so long as the vertical component of the tension within the mooring lines 36 remains greater than the downward component exerted by the suspended foundation pads 27. Further, by maintaining chain 22 in a generally horizontal disposition, the disloding force against imbedded anchor 16 will be least effective toward mooring the anchor.

In the event the foundation pads 27 are displaced by a severe stonn or the like, they can readily be repositioned merely by raising the same from the ocean floor and transporting to a desired location.

Obviously, many modifications and variations of the invention, as hereinafter set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A floatable mooring for a vessel positioned in a body of water, said mooring being adapted to movably adjust when subjected to excessive loading by said vessel at such time as the latter is connected to the mooring upper end, said floatable mooring comprising,

1. an elongated buoyant column, being normally urged to a substantially upright disposition in said body of water when said column is not subjected to a mooring load due to said vessel being connected at the upper end thereof,

2. said buoyant column having a length exceeding the depth of said body of water and including opposed upper and lower ends,

3. the said column upper end normally extending beyond the waters surface for engagement with a mooring line from said vessel,

4. a weighted foundation pad operably connected to the lower end of said elongated column by means of an upper ring embedded in said foundation pad and being of sufficient weight to overcome the buoyant force of the. latter whereby to maintain the column in said upright disposition, said foundation pad being supported at the floor of said body of water and a lower ring embedded in and extending from a side of said foundation pad below said upper ring,

5. a fixed anchor means positioned remote from said foundation pad, and being firmly embedded into said ocean floor,

. and a flexible connector member having one end thereof engaged to said fixed anchor means, the other end of said flexible connector being connected to said lower ring, whereby said connector member will normally rest at the ocean floor,

7. said buoyant column being pivotally displaceable when subjected to an excessive mooring force at the upper end, whereby to exert a tensional force on said flexible connector and said column respectively to thereby raise said foundation member from its resting place at said floor.

2. In a mooring device as defined in claim 1 wherein said flexible connector member comprises an anchor chain.

3. In a mooring device as defined in claim 1 wherein said elongatedbuoyant column includes a plurality of longitudinally disposed transverse panels forming said column into a plurality of buoyant compartments. 

1. A floatable mooring for a vessel positioned in a body of water, said mooring being adapted to movably adjust when subjected to excessive loading by said vessel at such time as the latter is connected to the mooring upper end, said floatable mooring comprising,
 1. an elongated buoyant column, being normally urged to a substantially upright disposition in said body of water when said column is not subjected to a mooring load due to said vessel being connected at the upper end thereof,
 2. said buoyant column having a length exceeding the depth of said body of water and including opposed upper and lower ends,
 3. the said column upper end normally extending beyOnd the water''s surface for engagement with a mooring line from said vessel,
 4. a weighted foundation pad operably connected to the lower end of said elongated column by means of an upper ring embedded in said foundation pad and being of sufficient weight to overcome the buoyant force of the latter whereby to maintain the column in said upright disposition, said foundation pad being supported at the floor of said body of water and a lower ring embedded in and extending from a side of said foundation pad below said upper ring,
 5. a fixed anchor means positioned remote from said foundation pad, and being firmly embedded into said ocean floor,
 6. and a flexible connector member having one end thereof engaged to said fixed anchor means, the other end of said flexible connector being connected to said lower ring, whereby said connector member will normally rest at the ocean floor,
 7. said buoyant column being pivotally displaceable when subjected to an excessive mooring force at the upper end, whereby to exert a tensional force on said flexible connector and said column respectively to thereby raise said foundation member from its resting place at said floor.
 2. In a mooring device as defined in claim 1 wherein said flexible connector member comprises an anchor chain.
 2. said buoyant column having a length exceeding the depth of said body of water and including opposed upper and lower ends,
 3. the said column upper end normally extending beyOnd the water''s surface for engagement with a mooring line from said vessel,
 3. In a mooring device as defined in claim 1 wherein said elongated buoyant column includes a plurality of longitudinally disposed transverse panels forming said column into a plurality of buoyant compartments.
 4. a weighted foundation pad operably connected to the lower end of said elongated column by means of an upper ring embedded in said foundation pad and being of sufficient weight to overcome the buoyant force of the latter whereby to maintain the column in said upright disposition, said foundation pad being supported at the floor of said body of water and a lower ring embedded in and extending from a side of said foundation pad below said upper ring,
 5. a fixed anchor means positioned remote from said foundation pad, and being firmly embedded into said ocean floor,
 6. and a flexible connector member having one end thereof engaged to said fixed anchor means, the other end of said flexible connector being connected to said lower ring, whereby said connector member will normally rest at the ocean floor,
 7. said buoyant column being pivotally displaceable when subjected to an excessive mooring force at the upper end, whereby to exert a tensional force on said flexible connector and said column respectively to thereby raise said foundation member from its resting place at said floor. 